In the field of solar heat utilization, there are an all-glass vacuum heat collection tube, and a vacuum heat collection tube with two open ends formed by sheathing an evacuated glass tube at the outside of a metal tube with two open ends at present, the shortcomings of this vacuum heat collection tube with two open ends lie in that as the evacuated glass tube must be double-layer, the manufacturing cost is high, in a use process, the inner layer glass is close to the metal tube coated with heat absorption coating, so the temperature of the inner layer glass is higher, and when the temperature of the outer layer glass is lower, a risk of bursting is caused by a larger temperature difference of the inner layer glass and the outer layer glass.
Therefore, the vacuum tube composed of double-layer glass is changed into a single-layer glass tube, and both ends of the single-layer glass tube are welded and hermetically connected to an expansion alloy ring, a metal corrugated pipe, a metal ring and the two end parts of the metal tube with two open ends successively through low temperature glass solder and a high temperature glass coating layer so as to form a hollow cavity with the outer surface of the coated metal tube with two open ends, vacuum is formed by vacuumizing, such a heat collector has a simple structure and is easy to seal, but as the glass tube is used, the risk of bursting is still not avoided. In addition, the heat transfer medium in the metal tube will expand or shrink with the change of the external temperature, and dirt is generated on an inner wall of the metal tube after a long time and is difficult to clean.